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Topic Review (Newest First)

03-10-2007 08:35 PM

Classix_Lover

Quote:

Originally Posted by xntrik

First, you don't need a fan above 30 mph, so it shouldn't make any difference. If it made a difference it is probably because the electric fan was blocking the airflow.

Second, you don't know how hot the air is going across the fan clutch.,,,,,

because.....

Third, the fan clutch is so close to the radiator that air cannot flow across it readily, so it might not be working correctly. 1 1/2 inches minimum clearance is needed for airflow.

Fourth, you are probably going to have to use a Derale stainess flex fan with 2 1/2 inches pitch and make a shroud, since a factory shroud will be too long and not match to your blade position. The blade should only be 3/4 inch maximum into the shroud.

Actually I don't think you will need a shroud if you use a high pitch Derale fan blade 3/4 inch from the radiator. I didn't.

I can hold my hand 10 inches in front of the radiator and feel the air pulling in with the engine at idle. I have never had a problem at 100+* and idling with the AC on. No shroud.

Sorry I missed your picture earlier.......

Dude... when I said I noticed a massive cooling improvement when moving, I meant I could easily see how the belt driven fan would help bring the temperatures down much faster compared to the mediocre electric fans. It's obvious that mass airflow past 30 mph should be more than adequate to cool it, I wasn't questioning that.

And no, I'm not going to get a flex fan. I don't care for them whatsoever. What's to stop me from fabbing up a shroud in the first place? I already mentioned numerous times that I'm building it up from scratch; I'm not searching in the junkyard for one to make it work.

Also, I'm not so sure about your theory about the clutch not getting proper airflow to it.

, everything spun true and of course massive cooling improvement at higher speeds compared to the other mediocre electric fans.

Once again, let it idle for a good while. Shut it off and imediately grabbed the fan blades to spin it and whaddya knowwww! The damn thing is STILL freewheeling and not properly locking up.

.?

First, you don't need a fan above 30 mph, so it shouldn't make any difference. If it made a difference it is probably because the electric fan was blocking the airflow.

Second, you don't know how hot the air is going across the fan clutch.,,,,,

because.....

Third, the fan clutch is so close to the radiator that air cannot flow across it readily, so it might not be working correctly. 1 1/2 inches minimum clearance is needed for airflow.

Fourth, you are probably going to have to use a Derale stainess flex fan with 2 1/2 inches pitch and make a shroud, since a factory shroud will be too long and not match to your blade position. The blade should only be 3/4 inch maximum into the shroud.

Actually I don't think you will need a shroud if you use a high pitch Derale fan blade 3/4 inch from the radiator. I didn't.

I can hold my hand 10 inches in front of the radiator and feel the air pulling in with the engine at idle. I have never had a problem at 100+* and idling with the AC on. No shroud.

Sorry I missed your picture earlier.......

03-09-2007 09:50 PM

Classix_Lover

Quote:

Originally Posted by Will H

Get a hair dryer or a heat gun and heat the thermostatic spring on the front of the clutch and see what happens, I think that you will find that the clutches you have are working correctly.

I did bake the clutch at 210* for over 30 minutes and pour hot water on the spring last night. I did see the spring move ever so slightly, but to just turn it by hand to tell the difference isn't going to work. Centrifugal forces are a key factor for this I'm sure, hence needing higher rpms to really see if everything's working correctly. It was misleading having people tell you it's supposed to lock up completely and not freewheel whatsoever when it's engaged kinda threw me off at first but everything's alright now. I'll keep this thread updated once I get around to fabbing up a custom shroud.

03-09-2007 09:47 PM

Classix_Lover

Quote:

Originally Posted by GMCTRUCKS

My 1970 GTO would run hot without the shroud even with a flex fan and it being one inch from radiator so I placed the shroud back and it was alright im going to see if this guy close to my house has an extra one I live right down the road from you off of FM-528 also how about using an electric fan that comes with a shroud you might want to check your timing as well.

Timing's just fine, I still need to fabricate the shroud. The main reason I was doing this test is to be sure the clutch was operating properly before I go through the trouble of fabbing up the shroud and just having to take everything apart if something wasn't operating correctly. Also, I did have a dual electric fan setup before but cooled inadequately; pos aftermarket thin fans, it's really no surprise why it likes to overheat at idle.

03-09-2007 03:23 PM

454C10

Another thing is to use the bypass hose and use the proper size hose (5/8's) and proper shape (pre-formed 90 degree). I recently had a 396 over heat when I didn't use the short bypass hose going from the water pump to the intake. I put the hose on and all the over heating problems went away.

For some reason, my 454 didn't need the bypass hose to run cool. But, I would put on a hoses if you aren't using one to see if that is the problem.

03-09-2007 02:48 PM

Will H

Get a hair dryer or a heat gun and heat the thermostatic spring on the front of the clutch and see what happens, I think that you will find that the clutches you have are working correctly.

03-09-2007 02:15 PM

454C10

I bought a cheapo haden at the local part store for less than 30.00. Standard duty for my BBC. Keeps my engine cool just fine and I live in south Texas.

Be careful which pilot shaft you get!!! 454 water pumps come in 1/2 inch or 5/8 shafts. You will have balance problems if you install a 5/8 shaft clutch on a 1/2 shaft water pump.

03-09-2007 01:19 PM

GMCTRUCKS

Fan

My 1970 GTO would run hot without the shroud even with a flex fan and it being one inch from radiator so I placed the shroud back and it was alright im going to see if this guy close to my house has an extra one I live right down the road from you off of FM-528 also how about using an electric fan that comes with a shroud you might want to check your timing as well.

03-08-2007 09:51 PM

Classix_Lover

As I talk more with my dad about this and think about it more, I don't know if it's physically possible to actually tell the spin difference just by grabbing on to the clutch and turning it by hand. I feel that centrifugal forces are necessary in order to see/hear it engage at higher speeds. Chances are, I just need to add a shroud but the main reason I've been wanting to see if it engages properly is so that I don't have to go through all the trouble of removing my shroud to replace a defective clutch. I guess I'll hang onto this for now, fabricate a shroud, and see where it goes from there. Anyway xntrik, I guess this thread is a good way to show people how to diagnose and test their clutches for problems. Thanks for the help all who contributed. Next step is shaving off a bit of the ends of the clutch fins to help it go in easier without scraping up my radiator. Had a hard time slipping the clutch out.

03-08-2007 09:04 PM

Classix_Lover

Quote:

Originally Posted by xntrik

All it takes is a good "turkey" baking thermometer..... might be one in that kitchen drawer.

We have a temperature gauge resting in the oven that verifies that it's the actual temperature. Took it out, spun it, no noticeable difference. Put it back in for some more time. That was about a 15 minute sitting btw.

03-08-2007 09:01 PM

xntrik

Quote:

Originally Posted by Classix_Lover

I'm doing something a little different for testing the clutch. I'm baking it at 210* in the oven for a nice good while to see if there is any noticeable difference in resistance to being turned. I was aware though about the engaging % diminishing over time. Good link though, thanks.

All it takes is a good "turkey" baking thermometer..... might be one in that kitchen drawer.

03-08-2007 08:56 PM

Classix_Lover

I'm doing something a little different for testing the clutch. I'm baking it at 210* in the oven for a nice good while to see if there is any noticeable difference in resistance to being turned. I was aware though about the engaging % diminishing over time. Good link though, thanks.

03-08-2007 08:31 PM

xntrik

Here's a little ditty that I just ran across, Look at page 2 for how to test fan clutch operation.

So what's going on? Is this really working correctly? I don't believe that it is. I noticed no difference in the free wheeling speed compared to before the heated test. What do you think I should do? Third times the charm right? Lol It's supposed to engage at 170* radiator air temperature, I let it get up to a bit over 210.